The present invention relates to a method of and apparatus for converting a flat blank into a box. More particularly this invention concerns the setting-up of such a machine for folding a flat normally cardboard blank into a semi-finished blank which is in collapsed state, ready to be folded out to assume a three-dimensional shape.
In the packaging industry it is standard practice to ship boxes in the form of collapsed semi-finished blanks which are folded by the user into the desired three-dimensional shape. A collapsed semi-finished blank is much easier to handle and ship than a set-up box.
Normally the conversion of flat blanks to semi-finished collapsed-box blanks is carried out in a large-scale operation by an automatic machine having a conveyor that displaces the flat blank through a plurality of treatment stations. Each of these stations is provided with a respective treatment element that creases the blank, folds it, applies adhesive or latex to it, or otherwise acts on it. Thus the flat blank in passing through these various treatment stations is converted into semi-finished collapsed-box blank which is ready to be transformed into a three-dimensional box.
For each different box to be set up it is normally necessary to perform a number of adjustment on the machine, frequently as many as ten. The various treatment elements must all be displaced normally transversely of the conveyor or conveyor path from the upstream end to the downstream end of the machine into positions corresponding to the seam lines, creases, or the like of a normally cardboard blank that is fed to the machine at the upstream end thereof. In the most common type of arrangement each of these treatment elements, which may be a creasing iron, a latexing roller, an inclined folder or the like is carried on a respective threaded spindle extending across the machine conveyor. Each of these spindles has at one end a handwheel that can be rotated to displace the respective treatment element in either transverse direction of the conveyor. Thus each of these handwheels is operated to set the respective treatment element at the respective location, then several blanks are run through the machine and readjustments are made until the machine is operating correctly and properly setting up the blanks.
A standard heavy-duty machine of this kind can produce as many as a hundred thousand semi-finished (i.e., collapsed but ready to be set up) boxes per hour. The adjusting operation takes normally a half-hour. Thus during this downtime a production capacity of fifty thousand boxes is lost. What is more it is frequently very difficult to establish the exact position for each of the treatment element in one operation. Thus it is normally necessary slowly to run the blank through the machine, stopping its conveyor with the blank in each of the treatment stations and then displacing a respective treatment element into the appropriate position. Thus in a typical machine five to ten separate adjustments must be made to set the machine up for a new blank. A machine of this general type is disclosed in German Allowed Application (DAS) No. 1,270,940, especially in FIGS. 2 and 3, to which reference may be had for information.